A series of metal chelating molecules, including the natural products enterobactin and mycelianamide will be synthesized. Three main objectives will be pursued in the course of our investigations: 1. The elucidation of factors which govern the stabiliy, chirality, and metal oxidation state of catechol and hydroxamate iron complexes. This objective will require the development of synthetic routes to a broad range of ligand systems. 2. The determination of ligand structural features which facilitate transport of chelating iron and subsequent release of iron in microbial systems. The mapping of the bacterial enterobactin receptor in this way will allow the design of antibiotics which, upon chelation or iron, will be actively transported into the bacterial cell. 3. The determination of ligand structural features which facilitate excretion of chelated iron in iron-overloaded mammals. Ligands which are non-toxic, orally active and which do not promote bacterial growth are sought for the treatment of secondary hemochromatosis.